In many manufacturing operations, particularly in the manufacture of cylindrical containers, such as two-piece steel cans, it is necessary to mass transport such articles, either in single file or side by side. Such containers are characteristically unstable, particularly at present-day line speeds which are capable of handling up to approximately 2,500 articles per minute.
Present-day two-piece steel cans possess can bodies having almost paper-thin side walls. During processing, the can bodies are caused to engage a number of work areas, including washing, decorating and necking stations. When moving from one station to the next, the can bodies either travel in a moving belt, or more advantageously, upon an air conveyor consisting of a plenum having openings for the directional supply of air from the upper deck surface. Devices of this nature are described in U.S. Pat. No. 4,456,406, the disclosure of which is incorporated herein by reference. However, it is often times necessary to change the vertical orientation of the can bodies as well as to convert the flow of cans from a multi-row configuration to a single file orientation, particularly when the can bodies are to be decorated and necked.
Air single filers, euphemistically known as doubling boxes, are well known in can processing operations. For example, one such device is disclosed in U.S. Pat. No. 4,182,586, the disclosure of which is hereby incorporated by reference. Conventionally, the input or upstream end of the air single filer would be fed by a waterfall which, as the name implies, simply consists of a curved slide which transcribes a circular drum across which cans travel while rotating 90.degree. to achieve horizontal orientation at which point they fall into the upstream end of the single filer. A curved top guide surface prevents the cans from tumbling due to the small clearance between the guide and the top of the can.
The use of a waterfall in feeding a single filer, or in feeding any other device for that matter, possesses a number of inherent shortcomings. Quite obviously, the dropping of cans en masse from a waterfall to a lower collection area can and often times does result in damage being inflicted to the container side walls. This is a particular problem today as steel beverage containers have been provided with very thin side walls as a material saving expedient.
When the flow of container bodies was to be interrupted, prior waterfall installations would employ a gate which would physically impede the entrance to the single filer which, itself, often times causes can damage. The gate regulates can flow by capturing a row of cans laterally across the conveyer with a pressure pad that clamps the row of cans between the pad and the conveyor deck surface. When the gate is closed, the pad is applied which clamps the cans, thus stopping the flow. When the gate is open, the pad is released and the cans are free to move. The clamping action applies a force to the can bodies which can result in their damage. The sliding action of the cans through a prior waterfall can cause damage to the open end of the can as it slides on the top guide.
It is thus an object of the present invention to provide a drum assembly and its method of operation as a substitute for waterfall installations of the prior art.
It is a further object of the present invention to provide a drum assembly and its method of operation capable of rotating steel can bodies in side-by-side relationship from a first to a second location over a curved surface while avoiding damage to the can bodies and providing a positive means of flow control while avoiding gate structures employed by the prior art.
These and further objects will be readily apparent to persons skilled in the art from the following specification and claims.